National security driving a Helium-3 shortage, hurting physics

Helium-3 is a rare isotope of the noble gas with applications in quantum …

The annual meeting of the American Association for the Advancement of Science just took place in Washington, DC, located in a convention center just opposite my favourite bar. I'm going to start off my coverage with news of a resource shortage you may not have heard of, but one with some wide-ranging implications for national security, supercool physics, and pulmonary research. What do these three quite different fields have in common? The answer is helium-3, or 3He, and the problem is there's just not much of it left.

Regular 4He, the kind that makes your voice sound funny and your kid's balloons float, is the first of the noble gases. It has two protons, two neutrons, and two electrons. 3He, however, has two protons but only one neutron, which gives it several interesting properties. First, it can be used as a neutron detector, since 3He has a large collision cross-section for neutrons. When a neutron meets an 3He atom, they react to form tritium (3H, an isotope of hydrogen with one proton, one electron, and two neutrons), and a hydrogen atom (1H, one proton and one electron), giving off energy in the process. There are several applications for sensing neutrons, the main being nuclear threat detection.

Secondly, 3He can be supercooled to temperatures very close to absolute zero, at which point it becomes a superfluid capable of being measured in microKelvins (µKs). With zero viscosity, superfluid 3He will actually climb up and over the walls of its container, which is a neat party trick, but also gives physicists insights into fundamental quantum behaviors. Both the 1996 and 2003 Nobel Prizes in Physics were awarded for research on superfluid 3He. Many refrigeration systems also use the gas to bring other substances down to near absolute zero.

Finally, 3He is a nontoxic gas with a high diffusion coefficient, so it's proven to be quite useful in lung imaging studies. Using MRI machines, it's possible to use 3He to quantify ventilation in different regions of the lung, allowing researchers to detect differences in lung function (say, between normal, asthmatic, and COPD lungs) with far greater spatial and temporal resolution than other methods. It's even possible to measure the microstructures of individual alveoli, the smallest compartments in the lung.

If this were August 2001, there'd be one less Nobel prize to talk about, but more importantly this post wouldn't have needed to be written at all. Although the only source of 3He its appearance as a by-product of nuclear weapons maintenance, there was more than enough of the stuff being stockpiled, and the Department of Energy was hard pressed to sell it for more than $100 per liter. In September of 2001, however, a number of people did something wicked over the skies of America, and all that changed.

The demand for nuclear detectors exploded (if you'll pardon the expression) from 8,000l/year to ten times that in 2008. A once-large stockpile rapidly dwindled and, to make matters worse, the reduction in the US nuclear weapons inventory and half-lives doing their thing have meant that production has been utterly outstripped by demand.

So what can be done about the problem? Luckily, quite a few efforts are underway. Although the national security applications account for 95 percent of US 3He use, there are other ways to achieve the same end. Joe Glaser, from the National Nuclear Security Agency (NNSA), spoke about how this shortage has led to new science. NNSA has a number of different requirements for neutron detectors, from large portal monitors that are being installed in border crossings, seaports, and airports as part of the Second Line of Defense Program, to rugged portable units that can be used in the field.

Truck weigh-and-inspection station with radiation portal monitor.

Oak Ridge National Laboratory

For the static radiation portal monitors, like the one pictured at right, a number of solutions present themselves. Instead of 3He-filled tubes, BF3 can be used, if the boron has been enriched to around 90 percent 10B. These tubes are less sensitive than 3He; you need three tubes of BF3 to do the same work as a single 3He tube, and BF3 is a rather nasty gas, but it's readily available. Lining the detector tubes with a thin film of 10B allows you to avoid working with BF3, again relatively cheaply, although again these detectors are less sensitive than 3He.

Moving away from 10B, glass fibers doped with 6Li have a number of cool features. When neutrons meet the 6Li atoms, the resulting energy gets transferred into the fibers, which we can detect as light (just like the optical fibers that pipe sound between your hi-fi components). They detect both neutrons and gamma rays, and can be made in a range of shapes and sizes, including backpack systems.

Other interesting technologies that are further away from the market include new organic materials that can detect high-energy neutrons. Additionally, NNSA has caught the recycling bug, and believe that it can meet up to 20 percent of its needs by recycling old 3He tubes.

Sadly, unlike neutron detection, the nonsecurity applications of 3He don't have any replacements as Jason Woods of Washington University mentioned as he discussed the impact of the shortage on both low-temperature physics and MRI work. When the supplies of 3He ran out, it essentially put a stop to new science in some areas of low-temperature physics. The US government is rationing out its supplies of 3He, and groups with existing refrigerators are ahead of the threat detection people in the line, but work in this area will be slow going for a while.

For the medical imaging uses, alternatives like 129Xe have been tried with unsatisfactory results. But, happily, it turns out that exhaled 3He is quite easy to recover and recycle. Exhaled 3He is temporarily stored in a He-proof bag—the atoms are so small you can't use just any storage—and then purified cryogenically at 77K.

As for solving the shortage, a number of options exist, but almost none are economically viable. The nearest, most abundant source of 3He is our very own moon, but we'll have more than a little wait before regular shipments start flowing.

34 Reader Comments

the only source of 3He its appearance as a by-product of nuclear weapons maintenance

Specifically, 3He is the decay byproduct of Tritium (hydrogen with 1 proton and 2 neutrons). Tritium is the primary 'fuel' in fusion warheads and has a half life of something like 26 years or so. So the US stockpile of fusion warheads needs to be 'topped off' periodically. Ironically, the reason less is available, is that the arms limitations treaties we've entered into have reduced our fusion weapon stockpile immensely. Sort of ironic.

There is no technological workaround to the use of helium-3 in helium dilution refrigerators, they are really quite elegant, using the unique quantum mechanical properties of helium-3 and helium-4 to cool a working volume. He Dilution refrigerators are the only technology that can cool large working masses (ie kilograms and up) to milliKelvin temperatures.

A lot of the details in this article aren't quite right. Firstly, helium-4 also becomes superfluid, and at much more reasonable temperatures than helium-3 (about 2.17 K for 4He). Secondly, by far the largest use of helium 3 in low-temperature physics is as a refrigerant, rather than by people studying its properties. A helium dilution refrigerator requires on the order of several liters of helium 3 gas to operate (and about 4 times that much helium 4, plus whatever is used in the first-stage cooling systems to get the system down to 2ish K). While not exactly an off the shelf object, there are several hundred of these things built every year. Fortunately, they can run for several years on one charge of gas. Thirdly, talking about 'molecules' of helium 3 is pretty silly.

Finally, with regard to the last paragraph, you need to note that all of the helium three that we've used to date was manufactured; it's the decay product of tritium and was made as a byproduct of the nuclear weapons program. As the Cold War ended and nuclear stockpiles were substantially decreased, the production rate of "waste" helium 3 has fallen. If the demand for the stuff becomes sufficiently high, there's no fundamental reason why either the US or the Russians couldn't resume production by making tritium and letting it decay. Lots of practical reasons why that won't happen any time soon, between the cost and the proliferation issues, but it's certainly possible from a technical standpoint.

No biggie, noble gas molecules just happen to be monoatomic (zero bonds). Of course via MO theory you could say there is potentially a huge number of non-bonding molecular orbitals in a given He-3 sample

Anyway, I'm actually tired of hearing about this shortage -- though I certainly learned some interesting info from the coverage -- which means someone needs to hurry up and fix it. Here's my solution:

1. Physicists collaborate on an international facility in a neutral country (e.g. Switzerland) to make tritium and hence He-3.2. Other researchers bring their projects to be supercooled down to millikelvin, so no tritium or He-3 leaves the site.3. Those researchers travel really fast back to their own labs to perform experiments before their samples heat up.

This is worrying. Helium is just one of several elements for which supply may be running out, and some of them have much wider applications (e.g. earth metals). Do governments, and more importantly does the industry have any kind of backup plan for a time when for instance the price of Lithium (everything nowadays seems to use Li-Ion batteries) starts to skyrocket due to decreased production and increased demand?

This is worrying. Helium is just one of several elements for which supply may be running out, and some of them have much wider applications (e.g. earth metals). Do governments, and more importantly does the industry have any kind of backup plan for a time when for instance the price of Lithium (everything nowadays seems to use Li-Ion batteries) starts to skyrocket due to decreased production and increased demand?

No.

Why would they? Nobody is going to believe this running out of rare stuff thing is real. You can probably find a several professors (in economy and humanities) that will argue "running out of stuff" is only a theory. And endless flames online about how global scarcity is a scam by physicists and their left-wing friends in the government.

Finally, with regard to the last paragraph, you need to note that all of the helium three that we've used to date was manufactured; it's the decay product of tritium and was made as a byproduct of the nuclear weapons program. As the Cold War ended and nuclear stockpiles were substantially decreased, the production rate of "waste" helium 3 has fallen. If the demand for the stuff becomes sufficiently high, there's no fundamental reason why either the US or the Russians couldn't resume production by making tritium and letting it decay. Lots of practical reasons why that won't happen any time soon, between the cost and the proliferation issues, but it's certainly possible from a technical standpoint.

Cost would be the real killer. Tritium currently costs ~$100k/gram, unless that represents an enormous markup, no one other than national security customers would be able to afford He3 produced directly this way.

This is worrying. Helium is just one of several elements for which supply may be running out, and some of them have much wider applications (e.g. earth metals). Do governments, and more importantly does the industry have any kind of backup plan for a time when for instance the price of Lithium (everything nowadays seems to use Li-Ion batteries) starts to skyrocket due to decreased production and increased demand?

No.

Why would they? Nobody is going to believe this running out of rare stuff thing is real. You can probably find a several professors (in economy and humanities) that will argue "running out of stuff" is only a theory. And endless flames online about how global scarcity is a scam by physicists and their left-wing friends in the government.

LOL. I can understand that e.g. for oil industry people. But industries that use oil as a production factor have already (and logically, from a purely economic standpoint) started looking for alternatives. In the same way, the semiconductor, battery and other industries that may be affected by scarcity of raw materials have an economic incentive to prepare for the future. It's basic business management.

Nice article in that you have brought attention to the issue. You could also do an article on He-4. Where does this come from? How does the government manage it? Supply and demand and why the price keeps increasing. Advanced nuclear reactor concepts that would clear out the US supply. As others have pointed out, He-3 is manufactured and we can always make more, but we go through a lot more He-4 and that natural resource is being quickly depleted. It could make for an interesting read, I think the public should know more and our policy makers should have a better strategy for it.

If not...think about all of the money and resources that we've squandered looking for a threat that doesn't exist.

The answer to your question would be classified for security purposes. Most likely there has been fissile material detected (not a lot, probably less than 100 times) but no weapons. That's my guess.

As far as squandering goes, it comes down to morals to a large extent. Game theory suggests nuclear nations should use nuclear weaponry on nations attempting to join the club. The chance of preventing proliferation is very good in this scenario. However, the morality of the nuclear nations and their leaders come into play so the diplomatic policy is to just ask states developing wmd to stop. Since nuclear nations refuse to engage in the most effective method of nonproliferation, they resort to other methods, such as the detectors you point out as being wasteful. I agree it is wasteful, but it also kills less people in the mean time, and this time can be used for the iranians to overthrow their government (as a specific example).

This is worrying. Helium is just one of several elements for which supply may be running out, and some of them have much wider applications (e.g. earth metals). Do governments, and more importantly does the industry have any kind of backup plan for a time when for instance the price of Lithium (everything nowadays seems to use Li-Ion batteries) starts to skyrocket due to decreased production and increased demand?

Yes. There are quite a lot of exotic materials out there than can do the job of the current materials. There's quite a lot of people working on those types of problems in academia and in government labs.

No one is going to invest the money to bring those to market when there's still a cheap supply of conventional materials, but we're not going to wake up one day and say "Oh shit, the element X is gone/super expensive and we haven't even started looking at alternatives."

Did any of these detectors ever find any evidence of nuclear weapons?If not...think about all of the money and resources that we've squandered looking for a threat that doesn't exist.

and then "someone" detonates a nuke/dirty bomb soon after the detectors are gone, and various "expert" talking heads go "told you so"...

Then "someone" just has to wait for the supply of He3 to dwindle such that the nuclear detectors must go unused.

Or "someone" finds a way to get fissile material into the country without going through one of the detectors, for instance through one of our porous borders to the north or south.

vibedog wrote:

I agree it is wasteful, but it also kills less people in the mean time, and this time can be used for the iranians to overthrow their government (as a specific example).

Killing less people in the mean time assumes that "someone" wants to use a nuke in the first place and that there are ZERO opportunities to get fissile material into the country without going through such detectors.

Do you have any evidence Iran wants to nuke someone? I know everyone likes to crow about the "wipe Israel off the map" comment, but the land around Israel is holy land to Muslims, too, and I somehow doubt that they would think Allah would forgive them for nuking their own holy land.

I wouldn't necessarily say so. You'd have to know the movie ahead of not watching it. Also, the wording was vague. If anything, your comment has made the original subtle one into something patently obvious, which is strangely ironic.

Well, not the ones we have in this half of the century at least. Maybe later -- the nuclear fusion between deuterium and tritium is likely to be reaction any fusion power plants use, essentially as it's the one that puts out the most energy at the 'lowest' temperature. I should stress that tritium is particularly nasty (and rare) stuff -- iirc, there's something like 20kg of it on the planet, and it's a high activity radioactive source that is easily inhaled.

As an aside, it's worth pointing out that the mean velocity of these light gasses at temperatures close to "outside" is actually a fair bit greater than escape velocity of earth, which is one reason in many as to why we can't magically recover them from the atmosphere. Helium loss actually plays a fairly important role in the thermodynamics of the stratosphere, if I recall correctly...

The cost of H3 will probably be what gets industry to the moon before the US government gets back there.

Actually, H3 is the only substance on the moon where mining operations can be justified. Most stuff is not worth the fuel to get machines there and the stuff back, but the rarity of H3 increases its value above the cost to go and get it. (with current technology)

I wouldn't necessarily say so. You'd have to know the movie ahead of not watching it. Also, the wording was vague. If anything, your comment has made the original subtle one into something patently obvious, which is strangely ironic.

Yep, I didn't have a clue what it was on about before hugodrax mentioned the title of the movie, and the twist. Without that, I might well have forgotten all about the in-joke here, and one day seen the film in blissful ignorance. Now? Less likely...

On topic, thanks for folks with all the clarifications about 3He and 4He, and the cost of producing 3He direct from Tritium. I quite like the idea of asking Switzerland if they'll take on the role of producing and bottling 3He for everyone